This invention relates to protective masking of surfaces prior to the application of a material to adjacent surfaces, and more particularly to masking of the walls or walls and floor in a room prior to the spray application of acoustic plaster and the like to the ceiling.
The spray application of acoustic plaster or similar coatings to a ceiling necessitates the careful, thorough and complete protective masking of all other room surfaces prior to the spraying operation. In the past, such masking has been a particularly inefficient, time-consuming and awkward task and a long-felt need for an improved method and apparatus has existed.
The material ordinarily used to mask the walls and floor of a room whose ceiling is to be sprayed is a sheet of plastic film formed in a width wider than the height of walls commonly encountered. As an example, the normal height of walls (i.e., in offices or residences) is in the approximate range of from 7 to 9 feet, while a common width of the plastic film is 12 feet. For ease in transporting and handling the material, it is usually furnished to the acoustic ceiling contractor by the manufacturer in rolls having widths substantially less than the width of the material itself. This roll width reduction is accomplished by forming one or more lateral folds in the sheet (which may be several hundred feet long) along its length prior to longitudinally rolling the folded sheet around a cardboard tube. A variety of lateral fold patterns may be employed to reduce the width of the sheet prior to rolling. A common roll length (using a 12-foot wide sheet) is 3 feet.
Under a method commonly used to mask the walls in a room, the masking worker first unrolls and cuts from the roll a length of the folded material somewhat longer than the perimeter of the room to be sprayed. Without unfolding the detached length, he then positions it on the floor causing the folded material to extend completely around the room at the base of the walls.
In order to reach the top edges of the walls, the worker must attach multilegged stilts to his feet. However, once these stilts are attached, the worker cannot reach the floor when standing on them. For this reason, prior to attaching the stilts he must temporarily secure a corner of the masking material to a wall (well above the floor) so that he can reach the detached material after attaching the stilts.
After attaching the stilts, the worker (making a second trip around the room) secures a continuous length of masking tape to the walls around the perimeter of the room at the intersection between the walls and ceiling. Only a top portion of the tape is attached to the walls. The bottom portion must be left unsecured for subsequent attachment of a longitudinal edge of the masking sheet between the walls and this unsecured taped portion.
When the worker returns to the starting point of his taping operation he must make yet a third journey entirely around the room (on stilts) to lift and attach the masking sheet along the walls. The temporarily attached corner of the masking sheet is removed from the wall and lifted to the unsecured portion of the tape. Then the longitudinal edge of the masking sheet containing the previously attached corner is progressively tucked under the unsecured portion of the tape and attached thereto as the worker moves around the room for the third time. Extreme care must be taken in this phase of the wall masking operation to assure that there are no gaps left between the tape and the upper edge of the masking sheet which would later allow the sprayed material to contact the wall beneath the gap. Additionally, during the initial portion of this lifting-tucking-attaching operation, care must be exercised not to let the masking sheet fall to the floor where it cannot be reached without the worker removing his stilts.
It should be noted that under the prior method of masking walls described above, it is not feasible for one worker, without an assistant, to simultaneously attach the masking material and tape along a wall, thus the time-consuming separate taping and attaching steps are required.
Another problem encountered in the prior method arises from the nature of the masking material itself. Due to economic factors and because the masking tape will hold only a limited weight, the masking sheet is very thin (a common thickness being on the order of 0.00075") and thus can be difficult to manage when any appreciable length is unrolled, due to its extreme pliancy. This inherent problem can manifest itself acutely when the folded material is unrolled around the room prior to the taping step. The roll is usually carried around the room while the worker unrolls the material and deposits it along the walls. Because of its pliancy, the unrolled material has a marked tendency to become twisted and unfolded during such unrolling. This tendency often hinders the worker when he later attempts to lift an edge of the sheet up to the attached tape. Even a single twist in the unrolled material can greatly retard the attaching operation--sometimes to the point of requiring the worker to remove his stilts and again move around the room to untwist and untangle the folded sheet.
In masking the floor of the room (which may be accomplished before or after the masking of the walls), the worker unrolls and detaches one ore more lengths of the folded material (depending on the dimensions of the room) and unfolds the material across the floor. A situation often encountered is where one dimension of the room is greater than the width of the masking sheet. This situation requires that two (or more) lengths of material be used and results in an area of overlap between the unfolded sheets on the floor. This overlap area provides a potential area through which the sprayed material may enter during spraying. Because of this, the "opening" between the two sheets must be sealed (i.e., with tape) before spraying or the sprayer (whose attention is primarily on the ceiling during spraying) must exercise great care not to kick one sheet away from the other sheet while moving around the room, thus exposing the floor during spraying. Additionally, the unrolled material tends to twist and tangle prior to unfolding, just as in the wall masking operation. The described procedure is further complicated by the not unusual presence of furniture and other equipment in the room to be masked. Such furniture and equipment (for instance in existing areas being remodeled) is not ordinarily removed during the spraying operation. It thus must also be thoroughly and completely masked--usually by running the floor masking material along the floor, up over the furniture, back down to the floor, etc. It additionally constitutes "barriers" which must be maneuvered around by the worker (usually on stilts) during his several trips around the room.
When the difficulty and inefficiency in the masking of a single room under the prior method is multiplied by the several or many rooms often encountered in a masking and spraying project, it becomes apparent that an improved method and apparatus is needed--both for economic reasons and to improve the effectiveness of the masking effort.
Accordingly, it is an object of this invention to enable application of masking material in a simple and efficient manner that eliminates or minimizes above-mentioned problems.